Thread: Dome Lights
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Old 09-06-2009, 06:27 AM   #1
btwilson86
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Default Dome Lights

So I see it's a common problem for the dome lights to not work, thought I'd do a quick write up for how to check what's wrong with them. From my experience, it's always a bad ground...

As with all light circuits, check the simple stuff first. In this case, that would be things like a fuse or the bulbs themselves.

Dome lights are on 2 different circuits; one to turn them on when the door opens, the other when you press the button for the individual lights. Both circuits are powered by the same "+" source (red wire that plugs into the back of the assembly). This is usually not the issue (as long as you don't have any broken wire or anything). The + wire will run directly to the bulbs, as it does not switch on or off. You can check to see if it's good by using a multimeter to check continuity between the + pin the electrical connector plugs into, and the + contact on each bulb (the one that is centered on the butt of the bulb). If you have continuity, the + is good.

The automatic door light circuit is grounded by the black wire from the electrical plug. Through a combination of rivets and short lengths of wire, the ground runs through the rocker switch (to turn them on with the doors or to stay off) to the casing of each bulb. Once again, you can check to see if you're connection is good by checking continuity between the "-" pin the connector plugs into and the bulb housing (little part that the bulb sits in). Make sure the switch is in the "on when door's open" position, otherwise you will not have continuity.

The push button light circuit grounds through the dome light assembly mounting screws. Each light has it's own grounding screw, but both grounds are also connected with a wire so that if one is bad, they should both still work. Around the mounting hole of the plastic housing is a metal ring that is connected to the ground wires for the bulbs. It is very common for this ring to build up corrosion, thus breaking the ground connection. Give these a good cleaning, and verify you have continuity between the ring's and the bulb holders. Please note that you need to have the push button switches in the "on" position when you do this test.

If the continuity is good at all points, reassemble the dome light assembly. Make sure the 2 mounting screws that act as the grounds are free of dirt or other contaminants, as this can result in a poor connection. If after reassembly the lights still don't work, the problem is likely before the lights themselves and would require more in-depth troubleshooting.
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